Long bone/bone formation

Osteology

Study of bones; Greek osteon = bone

Arthrology

Study of joints; Greek arthron = joint

Axial skeleton

Bones along the central axis of the body; skull, vertebral column, ribs, sternum, and hyoid

Appendicular skeleton

Shoulder girdles, upper limbs, pelvic girdle, and lower limbs

Axial skeleton bone count

80 bones

Appendicular skeleton bone count

126 bones

Adult skeleton bone count

206 bones

Compact bone

Dense, hard bone tissue that forms the strong outer portion of bone

Spongy bone

Porous inner bone tissue containing a lattice-like framework and marrow spaces

Cancellous bone

Another name for spongy bone

Trabeculae

Small bony beams forming the lattice framework of cancellous/spongy bone and creating spaces for marrow

Trabeculae memory

Latin trabecula = small beam; think little support beams inside spongy bone

Diaphysis

Shaft of a long bone

Epiphysis

End portion of a long bone

Metaphysis

Region between the diaphysis and epiphysis; growth plate is located here in growing bone

Medullary cavity

Hollow central cavity within the shaft of a long bone that contains bone marrow

Medullary memory

Medulla = marrow/interior; think marrow cavity in the middle of the shaft

Periosteum

Tough outer covering of bone; peri = around + oste = bone

Nutrient foramen

Opening in a long bone through which nutrient blood vessels enter; Latin foramen = opening

Nutrient artery

Enters through the nutrient foramen and supplies much of the shaft and inner bone

Epiphyseal arteries

Blood vessels that enter near and supply the ends, or epiphyses, of long bones

Periosteal arteries

Blood vessels that supply the outer portions of bone through the periosteum

Long-bone blood supply

Nutrient artery = shaft/interior; epiphyseal arteries = ends; periosteal arteries = outer bone

Ossification

Process of bone formation; Latin os/ossis = bone

Intramembranous ossification

Bone develops directly from connective tissue membrane without a cartilage model first

Endochondral ossification

Bone develops by replacing a cartilage model; chondr = cartilage

Endochondral memory

Cartilage first → bone later

Primary ossification center

First ossification center; usually develops in the diaphysis before birth

Secondary ossification center

Develops in the epiphyses, usually later than the primary center

Primary vs secondary ossification

Primary = shaft/diaphysis; secondary = ends/epiphyses

Epiphyseal plate

Cartilaginous growth plate that allows a long bone to grow in length

Epiphyseal line

Ossified remnant of the growth plate after longitudinal growth ends

Growth plate relationship

Open epiphyseal plate = bone can still grow in length; closed plate becomes epiphyseal line

Full ossification

Generally taught as occurring by approximately age 21

Long-bone formation sequence

Primary ossification in diaphysis → secondary ossification in epiphyses → growth plate remains → growth plate eventually closes